The present invention relates to spray guns for applying coatings, and, in particular to air controls for high volume, low pressure (HVLP) spray guns. HVLP guns are commonly used to apply finish coats to painted or varnished products. As such, it is desirable that the coating be applied in an even and consistent manner. HVLP guns use air supplied by an external turbine to apply a fluid coating that hardens into a finish. Specifically, the HVLP gun is provided with a container for storing the fluid coating, while the external turbine supplies pressurized air to the gun to pressurize the container and to provide an atomization air jet in which the pressurized fluid is sprayed. The most aesthetically pleasing finishes are achieved when the volume of air flowing through the gun optimally vaporizes the fluid leaving the gun, thereby avoiding blotting or clustering of the sprayed fluid. Typically, HVLP guns are outfitted with multiple valves to control air and fluid flow through the gun. For example, a trigger-operated fluid valve is typically provided to vary the volume of fluid flowing through the gun. A separate on/off air valve is connected to the trigger to permit a fixed volume of air through the gun. Thus, a separate knob-operated valve must be provided to vary the volume of air flowing through the gun. Thus, an operator must adjust both the trigger and knob to obtain optimal vaporization of the sprayed finish coating. It is desirable to reduce the complexity of operating HVLP guns such that their use is more widely available to less skilled operators.